Two-stage relay



Allg 13, 1940- w. l.. McGRATH 2,211,701

TWO-STAGE RELAY Filed Nov. 25, 1938 Cmomeg Patented Aug. 13, 1940 TWO-STAGE RELAY William L. McGrath, St. Paul, Minn., assignor to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation ot Delaware Application November 25, 1938, Serial No. 242,329

12 Claims.

The present invention relates to improvements in electrically operated devices particularly electromagnets and control systems embodying improved forms of such devices. More specically,

the invention has to do with and has as its object the provision of electromagnets or relays which may be controlled by sensitive control instruments andwhich may require relativelyI heavy operating currents but do not necessitate that the operating current be carried by the instrument contacts. By reducing the amount of current which the instrtunent contacts must carry the instrument may be made smaller, more sensitive, and emcient and its life is greatly pro` longed.

Another object is to reduce the power necessary for operation of electromagnets and the like and to reduce heating of such devices while in operation.

Another object is to provide electrical control apparatus whereby sensitive condition responsive instruments adapted for use with only small currents can satisfactorily and efliciently control relatively heavy equipment drawing heavy load currents.

Another object is the provision of an electromagnetic device having auxiliary contacts operated by an auxiliary armature, the auxiliary armature and contacts being controlled by a sensitive control instrument and the said auxiliary armature and contacts controlling energization of the electromagnetic device necessary for moving a main armature.

A detailed disclosure of representative forms of my invention may be found in the accompanying drawing and specification.

Figure 1 is a diagrammatic view of a system embodying my improved relay and including the electrical circuit wiring,

Figure 2 is a detail view of the auxiliary contacting arrangement of Figure 1,

Figure 3' is a view of the main part of Figure 1 with the parts in another position.

45 Figure 4 is another view of the structure of Figure 1 showing the parts in still another position,

Figure 5 is similar to Figure 3 but showing the parts in a still further position, and Figure 6 is a sectional view of another embodiment of my invention.

' Referring to Figure 1 of the drawing, numeral I0 designates generally a preferred form of my improved relay used in combination with a thermostat for controlling a compressor motor. The

relay I 0 comprises a generally U shaped core I I of magnetic material positioned horizontally and a main armature I2 which is pivoted to the lower leg of the core I I by means of a pivot pin I3. Wound on the upper leg of the core II are two separate 5 coil windings I4 and I5, the coil I4 having relatively high resistance and coil I5 having relatively low resistance. Carried by the main armature I2 is a smaller auxiliary armature IB which is attached to the main armature I2 by lo a exible leaf or bracket I'I fastened to the main armature by a rivet or the like. The core I I may be made of suitable conventional magnetic material of which cores are made and the armatures 15 IB and I2 may be made of soft iron or the like of which armatures are conventionally made. Adjacent the extremity of the upper leg of the core II is a pair of flexible contact carrying members 20 and 2| which may be suitably supported in any convenient manner (see Fig. 2). The members 20 20 and 2| are insulated from each other and they support electrical contacts 22 and 23, respectively. The auxiliary armature I6 carries a contact bar 24 supported by a carrying member or bracket 25 attached to the auxiliary arma- 25 ture. As will presently 'be explained in the description of operation following, the auxiliary armature Il may be moved to an in position in contact with the extremity of the upper leg of the core II when one or both of the coils I 4 and 30 I5 are energized, and when the auxiliary armature I6 is in its in position the contact bar 24 is in a position bridging the electrical contacts 22 and 23. The main armature I2 carries at its upper end a contact actuating bracket 26 of right 35 angular conguration as seen on the drawing. As will Ipresently become apparent, the main armature I2 may also be moved inI a` counter-clockwise direction into an in position by energization of the coils I4 and I5 and in this position of the 40 parts as shown in Figure 4 the contact actuating bracket 2B engages with the exible contact carrying members 20 and 2l and moves them out of engagement with the contact bar 24.

The main armature I2 has a. contact carrying member 21 supported at its lower portion, the contact carrying member 21 having a contact 28 which moves into engagement with a fixedcontact 29 when the main armature I2 is moved in 50 a counter-clockwise direction into its in position. 'I'he contact 29 is supported by a contact bracket or contact carrying member 30 which may be suitably supported in any convenient manner.

The contacts 28 and 29 form load contacts con- 55 lto trolling the energization and deenergization of the compressor motor shown at 3|. The motor 3| has been illustrated as a compressor motor merely by way of example, it being apparent that the contacts l28 and 29 might control any other form of electrical load.

Numeral 35 indicates generally a bimetallic thermostat of conventional type comprising a bimetallic element 36 having attached thereto a switch blade 3'I cooperating with a xed electrical contact 38. Adjacent the blade 3'I is a permanent magnetV 39 which causes the blade 3l to engage with and disengage from the contact 38 with snap movements, the details of the thermostat forming no part of my invention.

In operation, when blade 3'I of thermostat 35 engages contact 38 which it may do at a predetermined temperature for which the thermostat is set, a circuit is completed for energizing the coil Id of relatively high resistance as follows: from wire I through thermostatic element 36, blade 31, fixed contact 38, wire 02, coil I0, wire 03, to wire d0, the wires 0I and 06 being connected to any suitable source of power (not shown). As pointed out above the coil I6 is of relatively high resistance and will permit only sulcient current to flow therethrough to create enough magnetomotive force to cause-the auxiliary armature to be moved to the left to its in position as shown in Figure 3, the magnetic flux completing a magnetic circuit through the core Il, the auxiliary armature I6 and part of the main armature I2. Figure 3 shows the structure with the parts in the position they assume the moment after the thermostat 35 energizes coil I6. It will be seen that in Figure 3 zontact bar 20 is bridging contacts 22 and 23 and acircuit is thereby completed energizing the coil I as follows: from wire 3| to wire 45, contact bracket 2I,.( see.Figure 2) contact 23, contact bar 26, contact- 22, contact bracket 20, wire 46, coil I5, wire 47, back to wire 44. Upon completion of this circuit the coil I5 is energized and as pointed out above this coil is of relatively low resistance and permits a flow of current therethrough suiicient to create a magnetomotive force somewhat greater than that created by energizatio'n of the coil I0. The magnetic ux produced by the coil I5 follows substantially the same magnetic circuit as the ux produced by the coil I4 and the combined magnetomotive forces produced by the two coils are sucient to cause the main armature I2 to be rotated in a counter-clockwise direction thereby moving it to its in position as shown in Figure 4. With the main armature I2 in its in position as seen in Figure 4, the contact actuating bracket 26 engages the contact brackets 20 and 2| and move the contacts 22 and 23 out of engagement with the contact bar 24 in the manner described above in the structural description. As contact -bar 24 no longer bridgescontacts 22 and 23 the above described circuit therethrough energizing coil I5 is interrupted.v Coil I5 being deenergized the total amount of magnetomotive force produced by the device is reduced to that created by the high resistance coil I4 which remains energized through the thermostat 35. The main armature I2 will remain at present in its position as shown in Figure 4, however, because the magnetomotive force produced by coil I4, while being relatively small, is suflicient to maintain amature I2 in its in position although it would not be sufficient to cause armature I2 to move about 'its pivot into in position. lAs soon as armature I2 reaches its in position, contacts 28 and 29 are brought together completing a circuit for energizing the compressor motor as follows: from wire 0I lthrough wire 50, contact bracket 21, contact 28,

contact 28, bracket 30, wire 5I, motor 3|, and wire 52 back to wire Mi. From the foregoing, it will be seen that contacts 28 and 26 carry the load current for motor 3I which may be a relatively heavy current and which would be injurious to the contacts of thermostat 35 if it were permitted to flow through them. In my arrangement the load current is not even permitted to momentarily flow through the thermostatic contacts. The only current which the thermostatic contacts are required to carry is that relatively small current which the coil Id draws. The current which energizes coil I5 flows only momentarily through the contacts of Figure 2 thereby reducing the injurious eiect of such current to a minimum and reducing to a minimum the total amount of power required for operation of the relay.

Figure 5 shows the structure with the parts in the position they are in at the instant that the thermostat 35 has separated its contacts and interrupted the circuit therethrough. Deenergization of coil I has released the main armature I2 and it has started to move in a clockwise direction so as to separate the contacts 28 and 29.

The advantages and utility of my invention as so far disclosed should be apparent from the foregoing.A I employ a very small and sensitive thermostat for controlling a relatively great electricai load without subjecting the thermostatic contacts to heavy currents and without using more than a negligible amount of power for operation of the relay.

Figure 6 shows a second embodiment of my invention wherein I have employed its principles in an electrically actuated valve. Numeral |00 designates a valve body having the usual transverse partition IOI separating the inlet from the outlet of the valve, the partition IOI having a horizontal portion with an opening therein ilorming a valve port |02. The upper part of the valve body forms a flat cylindrical ange |03 the edges of which are screw-threaded and which is susceptible to the passage of magneticl ilux therethrough. Numeral |04 designates an inverted r cup-shaped casing or housing made of magnetic material which engages in screw-threaded relation with the ange |03 and which encloses thel operating mechanism of the valve. Numeral |05 designates a coil winding of relatively low resistance enclosed within the lower portion of member |00 and corresponding to the coil I5 of the previous embodiment. Numeral |06 designates a second coil winding of relatively high resistance the valve .port |02- within the valve body |00. The upper end of the armature IIO has a projecting nger III of materially smaller diameter extending upwardly therefrom and loosely encircling this projecting nger is an.l iron ring. 7 5

H2 forming an auxiliary armature corresponding to the auxiliary armature |6 of the previous embodiment. Numeral H3 designates a disc made of insulating material and carrying a pair of electrical contacts H4 and H5, the disc H3 being supported on supports H6 and H'I and biased into engagement with the said supports by a small coil spring H8. The contacts H4 and H5 are connected by wires as show n to a pair of terminals H9 and |20 extending exteriorly of the member |04. With the parts of Figure 6 in the position shown, the auxiliary armature H2 is below the magnetic center of the coil |06 and the main armature H0 is below the magnetic center of the twocoils |05 and |06.

The, thermostat of Figure 6 is identical with the thermostat 35 of the previous embodiment and whenever it closes bringing blade |31 into engagement with contact |38 a circuit is completed energizing the coil 06 as follows: from wire |4I to thermostat |35 through element |36, blade |31, contact |38, wire |42, coil |06, wire |43 back to wire |44. As soon as coil |06 is energized auxiliary armature H2 moves upwardly towards the center of magnetic attraction of coil |06 engaging with and bridging contacts Hdand H5, the magnetic ux circuit being through casing |04, ring |01 and the air gaps and armature within coil |06; The magnetomotive force of coil 06 is not of sulicient strength to cause auxiliary armature H2 to push disc H3 upwardly against the force of spring H8. Bridging of contacts H4 and H5 electrically connects the terminals H9 and |20 by reason of the wires which join the terminals H9 and |20 to the contacts H4 and'l I5, respectively. A circuit is thereby completed energizing coil |05 as follows: from wire |4| to thermostat |35, wire |45, terminals H9 and |20, wire |46, coil |05, and Wire |41 back to wire |44. The magnetic ilux produced by both the coils |05 and |06 combines in a single magnetic circuit through casing |04, flange |03, and the air gaps and armature within the coils having suicient magnetomotive force to move the armature H0 upwardly so that projecting finger H| engages the disc H3 forcing it upwardly against the bias of spring H8 moving the contacts H4 and H5 away from the auxiliary armature H2 and interrupting the circuit of the coil |05. Upward movement of both the auxiliary armature and main armature is limited by the supports H6 and H1 with which the disc H3 is normally in engagement. At the time of deenergization o-f coil |05 when the armature H0 is in its upward position, its upper end extends into the magnetic field produced by the coil |06 and the magnetomotive force of this coil is suicient to maintain the main armature H0 in its lifted position after it has been moved to that position by combined magnetomotive force of both coils. The lifted position of the armature H0 is shown in dotted lines in Figure 6, this position of course being open position of the valve. Whenever the thermostat |35 becomes satisfied, coil |06 is also deenergized and the armature H0 drops into closed position of the valve under the iniiuence of gravity, the spring H8 again forcing the disc H3 into engagement with the supports H6 and H1.

From the vforegoing those skilled in the art will appreciate that the embodiment of vFigure 6 is similar to the previous embodiment in that it has corresponding elementsand functions in a similar manner. The second embodiment also has the advantages and utilities pointed out in connection with the previous modication.

The disclosed embodiments of the invention are illustrative of various forms that the invention may take and of changes which may occur to those skilled in the art. The disclosure is to be interpreted in an illustrative rather than a limiting sense, the invention to be limited only in accordance with the appended claims.

I claim as my invention:

1. Electrical control apparatus for controlling relatively heavy load currents comprising in combination, electromagnetic means comprising, winding means, an auxiliary armature, and a main armature, means comprising load` contacts for carrying a relatively heavy load actuable by said main armature and auxiliary contacts actuable by said auxiliary armature, means comprising a sensitive thermostat having contacts adapted to handle only small currents, said last mentioned means comprising an electric circuit operable to energize said electromagnetic means sufficiently to produce a magnetomotive force great enough to operate said auxiliary armature whereby said auxiliary contacts become closed, closure of said auxiliary contacts completing an electrical circuit whereby said electromagnetic means is energized sufliciently to produce a magnetomotive force great enough to pull in said main armature whereby said load contacts are actuated, means associated with said main armature whereby upon pulling in of said main armature said last mentioned electrical circuit is interrupted, energization of said electromagnetic meansgby said means comprising a sensitive thermostat being suiiicient to maintain said main armature in its in position after it has been moved to its in position.

2. Electrical control apparatus adapted to be responsive to relatively small controlling currents comprising in combination electromagnetic means capable of being energized so as to produce various electromagnetomotive forces, said means comprising winding means, a main armature, an auxiliary armature, and auxiliary contactsactuable by said auxiliary armature, means comprising an electric circuit for energizing said electromagnetic means for producing a magnetomotive force great enough to move said auxiliary armature whereby said auxiliary contacts are actuated, actuation of. said auxiliary contacts completing an electric circuit to said electromagnetic means whereby a magnetomotive force l great enough to actuate said main armature into energized position is produced, means associated with said main armature for actuating said auxy armature, said auxiliary armature being relatively easily movable and said main armature requiring substantial force for moving it, said first winding being adapted upon energization thereof to produce a magnetomotive force great enough to move said auxiliary armature but not said main armature whereby said auxiliary contacts are actuated, actuation -of said auxiliary contacts bringing about energization of said second winding, said second winding producing a magnetomotive force which acting with the magnetomotive force of. said first winding actuates said main armature, means adapted upon movement of said main armature to open the circuit through said auxiliary contacts so as to deenergize said second winding,- said first Winding producing sumcient magnetomotive force to maintain said main armature in the position into which it was moved under the influence of the magnetomotive force of both windings.

4. In apparatus of the character vdescribed in combination, electromagnetic means comprising winding means, an auxiliary armature, a mainA armature, and auxiliary contacts actuable by the armatures, said auxiliary armature being movable to an in position for closing the auxiliary contacts and said main armature being movable to an in position for opening the auxiliary contacts, means comprising primary contacts for energizing said winding means only sufliciently to move said auxiliary armature to its in position, said auxiliary armature requiring only a small current iiow through said primary contacts for moving it to its in position, said auxiliary contacts closing upon movement of said auxiliary armature to its in position and completing an electrical circuit energizing said winding means suiiciently to move said main armature to its in position, said main armature requiring a relatively heavy current ilow through said auxiliary contacts for moving it to its in position, said main armature having means for opening said auxiliary contacts upen movement to its in position for interrupting said electrical circuit and terminating the energization of. said winding means brought about by said circuit, said auxiliary contacts having been only momentarily closed while said main armalarge current necessary for movement of said main armature `liever iiows through said primary contacts and only momentarily through said auxiliary contacts.

5. In apparatus of the character described, in

combination, electromagnetic means comprising winding means, an auxiliary armature, a main armature having load contacts actuable thereby and auxiliary contacting means actuable by said armatures, said contacting means comprising a movable contact member and a contact member actuable by said auxiliary armature, said auxiliary armature being movable to an in position for closing the contacting means and said main armature having means operative upon its being moved to its in position for moving said movable contact member away from said contact member actuable by said auxiliary armature and thereby opening said contacting means, means comprising Hprimary contacts for energizing said winding means only suftlciently to move said auxiliary armature to its in position, said auxiliary armature requiring only a small current flow through said primary contacts for moving it to its in position, said auxiliary contacting means closing upon movement of said auxiliary armature to its in position and completing an electrical circuit energizi 'g said winding means suliciently to move said main armature to its in position, said main armature requiring a relatively heavy current ow through said auxiliary contacts for moving it to its in position, said auxiliary contacting means opening upon movement of said main armature to its in position for interrupting said electrical circuit and terminating the energization of said winding means brought about by said circuit, said auxiliary contacting means having been only momentarily closed while said main armature was moving to its in position, and said primary contacts continuing energization of said winding means suiciently to maintain said main armature in its in position whereby the relatively large current necessary ior movement oi said main armature never flows through said primary contacts and only momentarily through said auxiliary contacts.

6. In apparatus of the character described, in combination, an electromagnetic device comprising winding means, a core member, a main armature pivoted thereto, and a smaller auxiliary armature movably attached to said main armature, contacting means actuable by said auxiliary armature, electrical means for energizing said winding means only suiciently to move said auxiliary armature whereby said contacting means become closed, said main armature remaining unmoved, said contacting means completing a circuit increasing the magnetomotive force produced by said winding means, said main armature is moved, means whereby upon movement of said main armature said circuit is interrupted, energization of said winding means by said electrical means exerting suflicient influence upon said main armature to maintain it in the position to which it was moved.

7. In apparatus of the character described, in combination, an'electromagnetic device comprising a core member, a first winding, a second winding, a main armature pivoted to said core, a smaller auxiliary armature movably attached to said main armature, contacting means actuable by said auxllian, armature, electrical means for energizing said rst winding, said rst winding drawing a relatively small current and producing enough magnetic effect to move said auxiliary armature but not said main armature, movement of said auxiliary armature actuating said contacting means whereby a circuit is completed energizing said second winding, energization of said second winding producing suflicient magnetic effect whereby said main armature is moved, means whereby movement of said main armature deenergizes said second winding, energization of said first winding being suiiicient to maintain said main armature in the position to which it was moved.

8. In a magnetic valve in combination, a rst solenoid winding, a second solenoid winding, an armature movable within said windings, said rst solenoid winding having-relatively little magnetic strength and said second solenoid winding having relatively greater magnetic strength, electrical means forv energizing said rst solenoid winding, means actuated in response to energization of said rst winding for energizing said second winding, the magnetomotive force of both windings combining to move said armature, means responsive to movement of said armature for deenergizing said second winding and said armature remaining in the position to which. it was moved as long as said first winding remains energized.

9. In a magnetic valve, in combination, a rst solenoid winding, a second solenoid winding, a main armature movable within said solenoid windings, an auxiliary armature movable upony energization of said first solenoid winding, said rst winding drawing a relatively small current and said auxiliary armature requiring relatively small forceA for moving it, means actuable by said auxiliary armature whereby upon energization of said rst winding said second winding is energized, said main armature moving in response to energization of both windings, means operable upon movement of said main armature for deenergizing said second winding, said first winding exerting sucient iniiuence upon said main armature to maintain it in the position t0 which it was moved under the influence of both windings.

10. In a. magnetic valve, in combination, solenoid mechanism comprising an operating coil and a holding coil cooperating with a movable plunger, an armature movable in response to energization of said holding coil, contacting means actuable by said armature, means for energizing said holding coil whereby said armature actuates said contacting meanscompleting a circuit energizing said operating coil, energization of said operating coil moving said plunger into the ileld of said holding coil, means actuated by said plunger for interrupting said circuit and deenergizing said operating coil upon movement of said plunger, said holding coil retaining said plunger in the position into which it was moved by said operating coil.

11. In a valve, in combination, a rst electrical Winding portion, a second electrical winding portion, an armature movable within said windings, said first winding portion having relatively little magnetic strength and said second winding-portion having relatively greater magnetic strength, electrical means for energizing said first winding portion, means actuated in response to energization of said first winding portion for energizing saidv second winding portion, said armature moving under the influence of the magnetic effect produced when said second winding portion is energized, means responsive to movement of said armature for deenergizing said second winding portion and said armature remaining in the position to which it was moved, as long as said first winding portion remains energized.

12. In a valve, in combination, a winding means, an armature movable within said winding means, said winding means being capable of producing various degrees of magnetic effect, means for energizing said winding means, means comprising electrical contacts actuatable in response to energization of said winding means for completing an electrical circuit increasing the magnetic effect produced by said winding means, said armature being movable in response to said increased magnetic eifect and operable to actuate said contacts to their original position, said armature remaining in the position to which it was moved.

WILLIAM L. MCGRATH. 

